成组叶片振动特性的三维数值模拟及实验研究

Three-Dimensional Numerical Simulation and Experimental Study on Vibratory Modes of Group Blades

采用三维8节点非协调单元,建立了成组叶片振动特性计算的三维有限元模型.该模型考虑到成组叶片位移约束的周期对称性,引入了斜边界条件和斜坐标系统来处理成组或整圈叶片的约束条件,从而可以准确地计算出三维复杂形状叶片组在动、静状态下的固有频率和振型.利用该方法对实例进行了计算,同时又在高速动平衡实验室进行了实验验证.计算结果和实验结果对比表明,用该方法计算的叶片振动特性精度较高,为计算复杂几何形状叶片组的振动特性提供了一种有效的手段.

A three-dimensional finite element model for the vibration analysis of group blades is presented. The model adopts a three-dimensional incompatible element with 8 nodes. In consideration of the cyclic symmetry of displacement constraints of group blades, a skew boundary condition and a skew coordinate system are introduced to deal with the constraint condition of group blades or integral blades. The model improves the calculation accuracy of natural frequencies and mode shapes of group blades, and offers an effective way for calculating the vibratory modes of integral blades with complex shape. The natural frequencies and modal shapes of a 4-blade group are computed under static and rotating conditions respectively. To verify the calculated model, a blade vibration experiment has been performed to measure the natural frequency of the blade group dynamically. The natural frequencies of the blade group at multiple running speeds are obtained, and the calculated results coincide with the experimental ones very well.